基于遥感的北方防风固沙区沙化草地利用基线盖度研究

    Study on baseline vegetation coverage of desertification grassland in northern sand-fixing region based on remote sensing

    • 摘要: 为推动北方防风固沙生态功能区稳定维持生态健康安全,满足草地资源适度利用协调发展,该文选择北方防风固沙生态功能区的正蓝旗为典型研究区,利用TM遥感影像的NDVI,结合大量的野外地面调查数据,建立植被盖度遥感反演模型,提取区域植被盖度,并按照沙地类型划分标准划分沙地类型,提取半固定沙地和固定沙地过渡带处的平均植被盖度,开展防风固沙功能基线盖度评估研究。以基线盖度为基准,划分非利用区和可适度放牧利用。结果显示,提取正蓝旗草地资源利用基线盖度为30.47%,并通过基线盖度地面调查验证,与基线盖度地面调查结果一致。确定了可适度利用的草原范围及面积为396 927.3 hm2,占正蓝旗草原面积的39%,建立了生态保护约束下的草地资源利用格局。该研究可为沙化草地合理利用提供参考。

       

      Abstract: Abstract: To promote ecology healthy, safe and steady development of sand-fixing ecological functional zone in northern China, and make the appropriate utilization of grassland resources with balanced and sustainable development, we take Zhenglan Banner as a typical instance of sand-fixing ecological functional zone in northern China to carry out research on baseline vegetation coverage of grassland. By using SPSS, the vegetation coverage remote sensing inversion model is established with normalized difference vegetation index (NDVI) extracted from Landsat TM images and plenty of synchronous field survey data. We use this model to extract the regional vegetation coverage of Zhenglan Banner, distinguish sand lands according to its criteria. With help of ArcGIS and ENVI, we extract spatial distribution data of half fixed sand land and fixed sand land respectively, and then convert data of half fixed sand-land and fixed sand-land to their distribution border polygon vector data. we obtain borderline of half fixed sand land and fixed sand land with polygon transformation tools provided by ArcGIS, and obtain line of intersection of half fixed and fixed sand land with intersection tools. With line of intersection and data of vegetation coverage distribution, we use statistical tools in ArcGIS to extract vegetation coverage corresponding to intersection line and count number of pixels of coverage. We obtain average of vegetation coverage from borderline between semi-fixed sandy land and fixed sandy land with their vegetation coverage and the corresponding number of pixel, and the average coverage of intersection line between two kinds of sandy land is taken as baseline coverage. With the baseline coverage, we regard sandy land which is less than value of baseline as substandard region, only those regions above baseline can be utilized appropriately. Experimental results show that average coverage of intergradation region between semi-fixed sandy land and fixed sandy land is 30.47%, which is verified with baseline coverage field survey. The vegetation coverage remote sensing inversion model was established with normalized difference vegetation index (NDVI) extracted from Landsat TM images and plenty of synchronous field survey data. Using this model, we extracted vegetation coverage of Zhenglan Banner. And then, the baseline coverage value was gained based on the boundary of the half fixed sand and fixed sand. The baseline coverage was set as the limited value, therefore, we can calculate the area of conservative grazing zone, that is 396,927.3 hectares, which is 39% of the grassland area in Zhenglan Banner. With data obtained in the experiments, structure of grassland resources utilization was constructed under constraint of ecological protection, which can provide a technical guarantee for promotion of well-balanced circulation of sand-fixing ecosystem, maintain service functions in region ecosystem and appropriately utilize region ecological resources in the north of China.

       

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